Patent GB-488892-A (GB)
Title: Process and apparatus for taking x-ray pictures of parts of the human body
IPC: H05G1/62
Filed: 1937-07-06
Abstract: 488,892. Valve relays. STRAUSS, S., and WEISGLASS, L. July 6, 1937, Nos. 18788 and 18789. Convention dates, July 8, 1936 and Oct. 17, 1936. [Class 40 (v)] [Also in Group XX] A radiographic process is characterized in that a plurality of short exposures are made in like phases of successive heart beats, the exposure moment of the individual exposures being controlled by the heart action itself by picking up from the body impulses dependent upon the heart action and actuating the X- ray machine by means of same after giving to said impulses an adjustable time delay. In the apparatus shown in Fig. 1 a compression cuff 1 is used as described in Specification 475,629 to transmit the pressure of the pulse to a diaphragm 2 and so to the piezo-electric crystal 3. The resulting E.M.F. is applied to a direct coupled amplifier consisting of valves 4 and 5 deriving their high tension voltages from a glow lamp voltage divider 8. The amplified voltages are applied to the relay 6. A condenser 12 is normally connected to a source of D.C. potential but when the relay 6 is operated it is discharged through a relay 10 which charges the condenser 13 from another source. This charge is shared with the condenser 15 through a variable resistance 14, and when, after a time depending on the setting of 14, the potential on 15 reaches a predetermined value a neon tube 16 strikes and the voltage across the resistance 17 is applied to the valve 18 and operates the relay 11 in the plate circuit. A condenser 22 and a resistance 21 are connected across the relay 11 and the resistance 21 is variable to determine the time during which the relay 11 is closed. While the relay 11 is closed the X-ray apparatus connected to R is operated through the contacts r. Through the contacts s the condenser 26 receives a charge, depending on the setting of the resistance 24. When the striking potential of a neon tube 25 is reached the relay 23 is closed and operates a device at A to indicate that sufficient exposure has been given, or to switch the X-ray apparatus off. The contacts h of the relay 11 are used to connect a condenser 19 and resistance 20 across the condenser 13 to reduce its potential and prevent more than one operation of the tube 16 from each closing of the relays 6 and 10. Fig. 2 shows portion III, of the apparatus of Fig. 1, modified to include a trap to prevent the apparatus being actuated twice when an abnormal heart beat closely follows a normal one. Extra contacts b, k, y are added to the relay 10 and i to relay 11. Closing of the contacts b charges through a resistance c, the condenser e in the grid circuit of the valve V. This valve normally carries anode current sufficient to hold the relay g and this is not released when the contacts b have closed once. In the event of the extra impulse referred to occurring the condenser e will receive a double charge, sufficient to bias V to its cut off point and release relay g, before the relay 11 closes and short circuits it through the contacts i. While the relay g is released contacts h<1> are closed and condenser 19 and resistance 20 are connected across condenser 13 to prevent the second impulse corresponding to the abnormal heart beat reaching the relay 11 to produce a corresponding exposure. The series of exposures is started by depressing the key X, Fig. 2. A relay m to ensure that the tube is not switched on in the middle of an exposure, is actuated by the contacts k or n and q in series, so that this relay is not operated until the closing of contacts k, but it remains closed until the key X is released. During this time the X-ray apparatus operated through the contacts o, p, r. The contacts y and z together may operate an electrical device, attached to B for the operation of the Bucky diaphragm in synchronism with the exposures. The Specification states that parts I and II of the apparatus shown in Fig. 1 may be replaced by any device, such as the electrocardiograph, for operating a relay in synchronism with the heart action. Specifications 446,031, [Group XIX], and 446,639 also are referred to.